The present invention relates to an apparatus for banding groups of palletized products, in particular palletized loads consisting of stacked products (such as, for example, but not restricted to, packs of bottles or other containers) to undergo intermediate processes and to be transported from one factory to another or from one processing station to another).
Apparatus of this type is used to wrap a band of material around a group of palletized products stacked to a certain height and relatively light in weight, in such a way as to stabilize the stack during its transportation from one processing line to another. The palletized load might consist, for example, of bottle crates placed side by side and stacked in two or more layers.
To stabilize a load of this type, the banding apparatus wraps a first band of plastic film at a certain height in order to hold the stack together at the most unstable part of it which would be the first to topple during transportation.
Prior art machines that perform banding operations this type comprise a gantry structure whose uprights mount a pair of film reels at a predetermined height. The film is unwound by suitable rollers in such a way that it is positioned transversely between the uprights to intercept the palletized load as the pallet moves under the gantry structure on a conveyor.
The forward motion of the pallet, after its front end has come into contact with the band of film, causes the reels to unwind so as to wrap the band around the sides of the products stacked on the pallet. As soon as the pallet has moved past the gantry, it is stopped and a unit comprising a sealer and a cutter, mounted behind the uprights, runs along the back of the pallet on suitable supports in a direction parallel to the rear face of the palletized load in such a way that the band of film is wrapped right around the palletized load. In other words, the film forms a loop around the upper section of the palletized product load and, since the film used is usually stretch film, also has a tightening effect which holds the load together.
At this point, the section of the band at the back of the palletized load is sealed and, as soon as this has been done, the cutter cuts the band half way between the two sealed ends: that means the looped band wrapped around the palletized load is closed, sealed and cut off, while the seal keeps the two reels joined to each other by the remaining film positioned transversely between the two uprights and ready to intercept the next palletized load moving forward on the conveyor.
At present, an increasingly frequent requirement is for banding machines to apply to the palletized load a second band of film, lower down than the first and bearing a distinguishing mark, such as a label identifying the products transported or their factory of origin.
To make applications of this type possible, the following have been added to banding machines:
a pair of reels mounted on the uprights of the gantry structure and designed to wrap a second band of plastic film, to which labels can be applied, at a fixed height relative to the uprights themselves; and
a second sealer and cutter assembly similar to the first assembly, and independent of it, mounted close to the base of the gantry structure and mobile in synchrony with the first assembly by means of two additional arms, designed to seal and cut the second band in the same way as the first.
This type of solution consists basically of a machine already well known in the trade with the simple addition of another pair of film reels and a second, fixed, independent unit but without adapting its constructional philosophy to suit the new requirement.
As a result, machines of this type are rather cumbersome, and adjusting the working heights of the sealing and cutting units is, at best, a highly complex operation (precisely because the units are independent of each other), which means that changeover down times have increased significantly).
Moreover, the second sealing unit at the bottom might be obstructed and unable to perform its work properly since existing pallet conveyors vary in height and in some cases cover the bottom section of the gantry structure that houses the second sealing unit.
The present invention has for an object to overcome the above mentioned disadvantages by providing an apparatus for banding palletized products that has a very compact structure, with sealing and cutting units which are quick and easy to adjust, that is adaptable to any conveyor and that operates in highly synchronized fashion.